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DESIGN OF LINEAR GENERATOR
NIK MOHD KAMIL B. NIK LAH @ NIK ABDULLAH
ELECTRICAL & ELECTRONICS ENGINEERING
UNIVERSITI TEKNOLOGI PETRONAS
SEPTEMBER 2012
DESIGN OF LINEAR GENERATOR
By
NIK MOHD KAMIL B. NIK LAH @ NIK ABDULLAH
FINAL PROJECT REPORT
Submitted to the Electrical & Electronics Engineering Department in Partial
Fulfilment of the Requirements for the Bachelor Degree of Engineering (Hons)
Electric & Electronics Engineering
Universiti Teknologi PETRONAS
Bandar Seri Iskandar
31750 Tronoh
Perak Darul Ridzuan
Copyright 2012
By
Nik Mohd Kamil Nik Lah
CERTIFICATION OF APPROVAL
DESIGN OF LINEAR GENERATOR
BY
NIK MOHD KAMIL B NIK LAH @ NIK ABDULLAH
A project dissertation submitted to the
Electrical & Electronics Engineering Department of
Universiti Teknologi PETRONAS
in partial fulfilment for the
Bachelor of Engineering (Hons) Electrical & Electronics Engineering
Approved by:
……………………………………
Assoc. Prof Dr Mohd Noh Karsiti
Project Supervisor
CERTIFICATION OF ORIGINALITY
This is to certify that I am responsible for the work submitted in this project, that the
original work is my own except as specified in the references and
acknowledgements, and that the original work contained here have not been
undertaken or done by unspecified sources or persons.
………………………………………………
Nik Mohd Kamil B Nik Lah @ Nik Abdullah
ACKNOWLEDGEMENT
Firstly I would like the express my token of appreciation to my Supervisor, AP Dr
Mohd Noh for the ideas and guides that he has contributed throughout the project. I
would also like to thank all the technicians involved either directly and indirectly in
this project for their assistants with the lab equipment and materials. Lastly, I would
like to thanks the University for the Facilities provided in the labs which the most
important part in making my project possible.
ABSTRACT
Linear Generator is one of the alternatives to the commonly used rotary
generator. For motion-based generator, the rotary type is widely used compared to
linear type because the momentum built up in a rotary motion is continuous. While
in linear motion, the momentum breaks at the end of the stroke. However, there are
some situations where linear generators can perform better than rotary generators
such as when the source of the motion itself is linear. If rotary type generator is to be
coupled to a linear motion, there will be a translation loss in the gearing mechanism.
Thus, the potential of Linear Generator must be further studied in order to extract
more output out of the available sources. This project is mainly about analysing the
known factors that affect the efficiency of a Linear Generator thus come up with the
best design for the generator. In general, there are many factors that need to be taken
into account in designing a Linear Generator. They can be grouped as Material,
Dimension and Components Configuration. The project will cover the study on the
Components Configuration on the efficiency of the generator. The Components
Configuration can be further broken into 3 smaller factors; Mover-Stator
Configuration, Magnet’s Configuration and Winding Configuration. Each of these
factors will be analyse in this project. For each sub-factors, a few designs has been
built and tested. The outputs (Voltage and Current) obtained from each design are
used to make comparison in order to get the best configuration for each category.
From the best design of each category, they will be combined to produce the best
design for the Linear Generator.
TABLE OF CONTENTS
CERTIFICATION
ABSTRACT
ACKNOWLEDGEMENT
CHAPTER 1: INTRODUCTION
1.1 Project Background 1 1.2 Problem Statement 2 1.3 Objectives 2 1.4 Scopes of Project 2
CHAPTER 2: LITERATURE REVIEW
2.1 Electromagnetic Theory 4 2.2 Principle of Induction Generator 6 2.3 Mover –Stator Configuration 7 2.4 Mover’s Magnet Configuration 8 2.5 Stator Winding Configuration 9
CHAPTER 3: METHODOLOGY
3.1 Project Flowchart 11 3.2 Project Activities 12 3.3 Prototypes 19 3.4 Testing Prototypes 21
CHAPTER 4: RESULTS & DISCUSSIONS
4.1 Mover-Stator Configuration 25 4.2 Magnet’s Mover Configuration 25 4.3 Stator Winding Configuration 26 4.4 Discussion 27 CHAPTER 5: RECOMMENDATION & CONCLUSION
4.1 Recommendation 29 4.2 Conclusion 31
REFERENCES 32
APPENDICES
LIST OF TABLES
Table 1 Table 1 Result for Experiment 1 15
Table 2 Result for Experiment 2 17
Table 3 Prototypes’ Profile 20
Table 3 Advantages and Disadvantages of Designs 25
Table 4 Prototypes’ Output Current and Voltage 26
LIST OF FIGURES
Figure 2.1 Magnetic field line 4
Figure 2.2 Moving Magnet 7
Figure 2.3 Moving Coil (external) 7
Figure 2.4 Moving Coil (internal) 7
Figure 2.5 Moving Iron Core 7
Figure 2.6 Mover’s Magnet Configuration 8
Figure 2.7 Vertically Coiled Winding 9
Figure 2.8 Horizontally Coiled Winding with Spacer 9
Figure 2.9 Horizontally Coiled Winding without Spacer ( Single Layer) 9
Figure 2.10 Horizontally Coiled Winding without Spacer (Multiple Layers) 10
Figure 2.11 Horizontally Coiled Winding (Twisted) 10
Figure 3.1 Flow Chart 11
Figure 3.2 The North pole meets the South Pole 12
Figure 3.3 Same Poles face the same direction 12
Figure 3.4 Poles arranged alternately 13
Figure 3.5 Hallbach Configuration 13
Figure 3.6 Experiment 1 Set Up 14
Figure 3.7 Experiment 2 Set Up 16
Figure 3.8 Output Voltage 17
Figure 3.9 Output Current 17
Figure 3.10 Design 1: Vertically Coiled Winding 19
Figure3.11 Design 2: Horizontally Coiled Winding with Spacer 19
Figure 3.12 Design 3: Horizontally Coiled Winding without Spacer
( Single Layer) 20
Figure 3.13 Design 4; Horizontally Coiled Winding without Spacer
(Multiple Layers) 20
Figure 3.14 Design 5: Horizontally Coiled Winding (Twisted) 20
Figure 3.15 Measuring Voltage Set up 21
Figure 3.16 Measuring Current set up 22
Figure 3.17 DataStudio Software 22
Figure 3.18 ScienceWorkshop 570 Interface 23
Figure 3.19 Current Sensor 23
Figure 3.20 Experiment set up 24
Figure 5.1 Ring and Segmented Magnet 30
1
Chapter 1
INTRODUCTION
1.1 Project Background
Since the early years of electricity discovery, researchers constantly improve the
technology of electrical generator in order to come up with the most efficient
generator which can produce the most electrical power out of a given source.
However, converting mechanical energy to electrical is energy is still the main
practice in the industry. Most electric generator still uses the concept of inducing
current from a moving conductor in a magnetic field.
Linear Generator is a less popular type of generator compared to the widely used
rotary type generator. Currently, Linear Generator is commercially used to generate
electricity from tidal waves. However, there are more situations where Linear
Generator can perform well or maybe even better than a rotary type generator. For
example, a car engine, the combustion of fuel in the cylinder pushes the piston
upward producing a linear motion which is later translated to rotary motions by
means of shafts and gears. A car dynamo which generates electricity for the car is
mounted on the rotary part. Let say, a linear generator is coupled directly to the
piston; the electricity generated will be free of mechanical losses from the translation
process.
Currently, there are many good designs available for a Linear Generator, but it
does not mean that it is the end for its development. The design can be improved
from time to time and that is the objective of the project.
2
1.2 Problem Statement
In general, there are many factors that need to be taken into account in designing
a Linear Generator. They can be grouped as Material, Dimension and Components
Configuration. The project will cover the study on the Components Configuration on
the efficiency of the generator.
1.3 Objective
• To analyse the effects of various component configuration on the
efficiency of the Linear Generator
• To come up with the best design by the combination of the best
configurations obtained from the analysis.
1.4 Scope of Study
The Components Configuration can be further broken into 3 smaller factors;
• Mover-Stator Configuration
• Magnet’s Configuration
• Winding Configuration.
Each of these sub-factors will be analyse in this project by testing various designs for
each sub-factor.
3
Chapter 2
LITERATURE REVIEW
Analysis of Tubular Linear Generator for Free-Piston Engine
Uses coil-wounded stator and permanent magnet mover. The magnet can be radial
magnet or in Halbach array. For a simple analysis, a ring shaped magnets are used.
Magnets are arranged with opposite poles facing each other with a spacer. The stator
coils also spaced with the same measurement. Advantage of tubular design is that it
is symmetric, has smaller leakage and less coils needed[5].
Permanent Magnet Linear Alternator, Part II : Design Guidelines
Permanent magnet excited tubular three phase linear alternator[6],
Stroke length where Sn = rated power
Electromagnetic thrust u = rated speed
Stator no-load volatage fe = electric frequency
Permanent Magnet Linear Generator for Renewable Energy Applications:
Tubular vs Four-sided Structure
Analysis between tubular design and four-sided structure, keeping the volume of the
magnet constant. Maximum magnetic flux in tubular design is slightly higher than
the four-sided design but the average magnetic flux are the same. Air gap length is
longer for four-sided structure. Four-sided structure has longer coils resulting in
higher loss[7].
4
Novel Permanent Magnet Linear Generator for Wave Energy Converter
Permanent magnet mover with spacer made of iron core of the same thickness of the
magnet. Coil on stator spaced by iron core-teeth with the same thickness as the
spacer in the mover. Second design, air-cored stator and ironless spacer with the
same dimension as the first design. First design; better output, second design; simpler
and less cost. [8]
2.1 ELECTROMAGNETIC THEORY
It is best to start the designing stage by understanding the magnetic field line of a
permanent magnet. For a normal bar-typed magnet, the field line is as shown in the
figure.
Figure 2.1 Magnetic field lines
The direction of the magnetic field line is from the North Pole to the South Pole. It
same for all types of magnet except for the shape of the line might varies depending
on the shape of the magnet.[1]
Magnetic Field Intensity
Current flowing through a conductor produces a magnetic field around the
conductor. The magnitude of the magnetic field on a given area is known as the
Magnetic Field Intensity, H.
5
Magnetic Induction
Magnetic induction is the force exerted on the current carrying conductor,B.
Where is the permeability of the medium. The unit for B is Tesla.
Magnetic Flux
Magnetic flux Ф is the magnetic induction passing through a surface. The magnetic
flux for a given surface S is:
Induced Emf,
Induced electromotive e force in a closed circuit is equal to the negative time
derivative of the total flux bound by the circuit.
Flux linkage
If the closed circuit is consist N turns close together, each intercepts the same
magnetic flux, the emf will add up in multiple of N. N is called the flux linkage Λ.
6
2.2 PRINCIPLE OF INDUCTION GENERATOR
An induction generator consists of 2 major components: stator and rotor.
Stator is the non-moving part of the generator while rotor comes from the rotating
part of a rotary generator. In this case, rotor will be called as mover. Other elements
connected to the stator and mover are the source of magnetic field (can either be a
permanent magnet or and induced magnetic field from current carrying conductor)
and coils where the current will be induced. Both the source and the coils can be
either on the mover or stator based on the respective design. In between the stator
and the mover, it is necessary to provide an air gap as to ensure a smooth movement
of the mover. It is also necessary to design the air gap to be as small as possible.
Smaller air gap makes the mover closer to the stator which results in stronger
magnetic field in contact with the coils. [3]
7
2.3 MOVER-STATOR CONFIGURATION
1. Moving Magnet
Coils will be wrapped around a structure (cage) and the mover (magnet) will
inside the cage and connected to a shaft which is connected to an external
moving force. [2]
Figure 2.2 Moving Magnet
2. Moving Coils.
Coils are connected to the external moving force while the magnet will be
mounted to a fixed position.
or
Figure 2.3 Moving Coil (external) Figure 2.4 Moving Coil (internal)
3. Moving Iron Core
Magnet on the outside will magnetize the iron core in the cage to make it a
temporary magnet. The temporary magnet will have its magnetic field cutting
across the coil.
Figure 2.5 Moving Iron Core
8
2.4 MOVER’S MAGNET CONFIGURATION
(a) Magnets without spacer (b) Magnets with spacer
Figure 2.6 Mover’s Magnet Configuration
Based on the designs from the literature review, most of the design uses a
configuration (a). Configuration (b) is an alternative where both will be compared
later on.
In design (a), the magnets are attached to each other where the magnetic flux
of each piece of magnet combines to produce 1 loop of magnetic flux coming out
from the north pole of the end-most magnet to the south pole of the magnet on the
other end.
In design (b), the magnets are separated by a certain distance far enough not
to let the flux to come across each other thus each magnet will have their own flux
line loop.
9
2.5 STATOR WINDING CONFIGURATION
1. Vertically Coiled Winding
Figure 2.7
2. Horizontally Coiled Winding with Spacer
Figure 2.8
3. Horizontally Coiled Winding without Spacer ( Single Layer)
Figure 2.9
10
4. Horizontally Coiled Winding without Spacer (Multiple Layers)
Figure 2.10
5. Horizontally Coiled Winding (Twisted)
Figure 2.11
11
Chapter 3
METHODOLOGIES
3.1 PROJECT FLOWCHART
Title Selection
Study on electromagnetic
theory & principle of
generator
Proposed design
Benchmark Experiment
Gathering materials
Build prototype
Testing Modification
Final Design
Recommendation
Figure 3.1
12
3.2 PROJECT ACTIVITIES
3.2.1 Determining the Magnets’ Configuration
By using Finite Element software, some simulations are done to observe the flux line
of the magnet based on different configuration. The results obtained are as follows:
1. The North pole meets the South Pole
Figure 3.2
From the figure shown, when the end meets the opposite end, the magnets act
like 1 magnet where the flux came out from the North pole of the outest magnet to
the South pole of the outest magnet on the other end.
2. Same Poles face the same direction
Figure 3.3
From the figure, when all the North pole of the magnets face upwards,
theflux line of the magnet in the middle goes straight upward as it has no path to
return while the other magnets’ flux line behave normally.
13
3. Poles arranged alternately
Figure 3.4
From this configuration, the flux lines have a complete path. However, since
the opposite pole is close to each other. The flux line is short and there might be no
flux crossing the conductor.
4. Hallbach Configuration
Figure 3.5
This configuration improves the first configuration in terms on the locations
of the flux crossing the conductor. From 3 magnets, 2 loops of flux lines are formed
compared to the first once which only 1 loop is formed.
Based on the simulation, the Hallbach configuration is selected. The magnetic
field of the magnets are directed to the centre magnet where it releases the flux to the
conductor. This method provides a better path for the flux line going out from the
North Pole to the South Pole of the magnet. The flux produced is much denser which
later will contribute to higher EMF produced when the conductor cut the flux lines.
14
3.2.2 Benchmarking Experiments
Experiment 1
Objective: to obtain a rough estimation of the output that will be produced by a small
size linear generator.
Apparatus and material:
• Winding (300 turns, 0.8mm copper wire, borrowed from the lab)
• Permanent magnet
• Multi-meter
16.3cm (cylinder) 300 turns coil
15.3cm (magnet)
Figure 3.6
Procedure
1. Ends of winding are connected to multi meter.
2. To obtain a constant speed for all runs, the magnet is set at a constant height
of 5cm above the winding. Then it is released in the winding with
gravitational acceleration.
3. Maximum voltage is recorded.
4. Steps 1 to 3 are repeated for 3 runs.
5. Steps 1 to 4 are repeated for current measurement.
N S
15
Results
Table 1 Result for Experiment 1
Run Voltage (V) Current (A)
1 0.30 0.30
2 0.30 0.30
3 0.28 0.30
16
Experiment 2
Objective: to test the self-made winding.
Apparatus and material:
• Winding (100 turns, 0.8mm copper wire, self-made)
• Permanent magnet
• Multi-meter
6.cm (cylinder) 100turns coil
15.3cm (magnet)
Figure 3.7
Procedure
1. Ends of winding are connected to multi meter.
2. To obtain a constant speed for all runs, the magnet is set at a constant height
of 5cm above the winding. Then it is released in the winding with
gravitational acceleration.
3. Maximum voltage is recorded.
4. Steps 1 to 3 are repeated for 3 runs.
5. Steps 1 to 4 are repeated for current measurement.
N S
17
Result: Voltage
Figure 3.8
Current
Figure 3.9
Table 2 Result for Experiment 2
Run Voltage (V) Current (A)
1 0.080 0.075
2 0.090 0.080
3 0.090 na
18
Discussion
For both experiment, a bar magnet is used instead of the magnet as per design
this is due to the strength of the magnet bought. The magnets bought satisfy the
requirement in terms of its shape and size. However, the strength of the magnet is too
weak, thus the magnetic field could not reach the coil causing no output. For the sake
of continuing the experiment, the magnet factor needs to be neglected for the time
being and only the effect of windings can be experimented.
From both experiment, it shows the effect of the number of turns of the coils.
In experiment 2, the no of turns is (100 turns) 1/3 of the 1st experiment (300 turns).
The output obtained from the 2nd experiment is (0.09V & 0.08A) and also almost 1/3
of the output from the 1st experiment (0.3V & 0.3A).
19
3.3 PROTOTYPES
1. Design 1: Vertically Coiled Winding
Figure 3.10
2. Design 2: Horizontally Coiled Winding with Spacer
Figure3.11
3. Design 3: Horizontally Coiled Winding without Spacer ( Single Layer)
Figure 3.12
20
4. Design 4; Horizontally Coiled Winding without Spacer (Multiple Layers)
Figure 3.13
5. Design 5: Horizontally Coiled Winding (Twisted)
Figure 3.14
Table 3 Prototypes’ Profile
Design Number Resistance Capacitance Inductance
1 27kΩ -38nF 168mH
2 53kΩ -94nF 66mH
3 67Ω 1uF 5mH
4 672Ω -204nF 31mH
5 300kΩ 0.6nF 9H
21
3.4 TESTING PROTOTYPES
Experiment 3
Objective
To measure the output current and voltage for each design.
Apparatus
Prototypes
Current Sensor
Connecting Wires
DataStudio Software
Science Workshop 750 Interface
Current Sensor (1ohm internal resistance)
Magnets
Part 1: Measuring Voltage
Procedure
1. The apparatus is set up as shown in the figure.
Prototype
Figure 3.15 Measuring Voltage Set up
2. Wires are connected to each end of the coil. The other ends of the wires are
connected to the port of Science Workshop 750 Interface.
3. Magnets are released from a height of 15cm into the coil.
4. The output recorded by the DataStudio is observed.
Computer
Science Workshop
750 Interface
22
Part 2: Measuring Current
Procedure
1. The apparatus is set up as shown in the figure.
Current Sensor
Prototype
Figure 3.16 Measuring Current set up
2. Wires are connected to each end of the coil. The other ends of the wires are
connected to the current sensor.
3. The current sensor is connected to the port of Science Workshop 750
Interface.
4. Magnets are released from a height of 15cm into the coil.
5. The output recorded by the DataStudio is observed.
Figure 3.17 DataStudio Software
Computer
Science Workshop
750 Interface
23
Figure 3.18 ScienceWorkshop 570 Interface
Figure 3.19 Current Sensor
24
Figure 3.20 Experiment Set Up
25
CHAPTER 4
RESULTS & DISCUSSIONS
4.1 MOVER-STATOR CONFIGURATION
Through discussions with the project supervisor, the outcomes of the discussion
are presented in the table below
Table 3 Advantages and Disadvantages of Designs
Design Advantage Disadvantage
Moving Magnet High flux density in contact with the coil Easy to establish connection for the coil
Magnet exposed to
physical contact, might
demagnetize by time
Moving Coil High flux density in contact with the coil
Complicated to establish
connection since the coils
is not stationary
Moving Iron Core Magnet safe from physical contact Easy to establish connection for the coil Iron core will not demagnetize as long as source magnet is available
Less flux density
4.2 MAGNET’S MOVER CONFIGURATION
Both yield the same output. Difference only in the stroke length as magnets with
spacer requires longer stroke length.
26
4.3 STATOR WINDING CONFIGURATION
The values tabulated below are based on the maximum magnitude (ignoring
the polarity) since only the objective of the experiment is too obtain the average
magnitude current and voltage produced by each design
Table 4 Prototypes’ Output Current and Voltage
Design 1 Run 1 Run 2 Run 3 Run 4 Average
Current (A) 0.15 0.09 0.10 0.06 0.100
Voltage (V) 0.07 0.11 0.14 0.04 0.090
Design 2 Run 1 Run 2 Run 3 Run 4 Average
Current (A) 0.12 0.05 0.14 0.08 0.098
Voltage (V) 0.30 0.20 0.30 0.30 0.275
Design 3 Run 1 Run 2 Run 3 Run 4 Average
Current (A) 0.04 0.035 0.03 0.05 0.038
Voltage (V) 0.15 0.18 0.30 0.28 0.228
Design 4 Run 1 Run 2 Run 3 Run 4 Average
Current (A) 0.05 0.08 0.07 0.07 0.068
voltage (V) 0.12 0.22 0.17 0.19 0.175
Design 5 Run 1 Run 2 Run 3 Run 4 Average
Current (A) N/A N/A N/A N/A N/A
voltage (V) 0.29 0.23 0.20 0.28 0.250
27
4.4 DISCUSSION
Design 1: Vertically Coiled Winding
In the experiment, Design No. 1 is the pioneer of the other designs. As per
advised by the Supervisor, the winding is coiled vertically and output is observed.
Design No 1 is actually a good design. However, its efficiency is affected by the
strength of the magnet. Theoretically, if the winding is too thick that it reaches a
point where the outer turns are no longer interact with the magnet’s magnetic flux,
the total area of the winding in contact with the magnetic flux is too small compared
to the total available. Thus the efficiency will be low.
Design 2: Horizontally Coiled Winding with Spacer
Design No. 2 is the extension of the previous design. It improves design No.1
by reducing the winding thickness and still maintains the number of turns. Both have
2000 turns, Design No. 1 has its 2000 turns in 1 slot. Design No.2 breaks down the
turns into 4 slots of 500 turns each. Each turns will be able to interact with the
magnetic flux thus increasing the efficiency compared to the previous design.
Design 3: Horizontally Coiled Winding without Spacer ( Single Layer)
Design No.3 on the other hand is the extension of design No.2. This time, the
thickness is drastically reduced to only 1 layer of winding in order to make sure that
all windings are in the reach of the flux line. However, in order to maintain the stroke
length, the number of turns is reduced to 500 turns. Theoretically, this design
produces a high amount of current with such a small number of turns which should
make it the best design for the configuration. However, the design is hard to
manufacture and the arrangement easily spoiled if exposed to physical contact (the
windings tends to overlap each other if in contact). Thus it cannot be finalized as the
best design.
28
Design 4: Horizontally Coiled Winding without Spacer (Multiple Layers)
Design No.4 is also the extension of design No.2 which reduces the winding
thickness while remaining the number of turns which in the end produces an
overlapping turns. The output obtained is not as good as the one obtained from
design No.2 due to the crossover between the wires. Based on Data & Computer
Network Theory, wires crossing over other wires may interrupt the data (voltage &
current signal) carried by the wire as each wires carries their own magnetic fields.
Crossover effect is prevented by twisting the wire (as normally seen in power cables
and signal cables) which brought us to the next design.
Design 5: Horizontally Coiled Winding (Twisted)
Design No.5 is supposed to improve design No.4. Based on the results
obtained, the design produced better output voltage compared to design No.4.
However, the output current of the design is not available. After a few tests done in
different sessions, the result was still the same. It might be due to unseen technical
error. The shown values in the graphs are the default values when the prototype was
connected to the interface of the software. Theoretically, this design should be a
promising design as its winding is fully in contact with the flux and there are fewer
crossovers between the turns. However, since the output is not available, the
efficiency of the design cannot be proved.
Based on the table, design No 1: Vertically Coiled Winding produced the highest
voltage while design No 2: Horizontally Coiled Winding (with spacer) produces the
highest current. In overall, design number 2 produced the highest output. Design
No.2 excels in both criteria while the other designs might excel in one criterion but
no in the other one. Thus, it can be concluded that the best configuration for
Components Configuration is design No 2.
29
CHAPTER 5
CONCLUSION & RECOMMENDATIONS
5.1 RECOMMENDATIONS
Based on the results obtained, the best design would be Design No.2:
Horizontally Coiled Winding with Spacer. The design can be further
improved by minimizing the size of the spacer so that more turns can be
made out of a given length. The role of the spacer in the design is to reduce
crossover between the turns which the main factor that causes Design No.4 to
not performing well. The alternative that can be used to replace the spacer
would be by tying the wires into bundles before coiling them to the cylinder.
When the wires are tied into bundles, they will only cross over with the other
wires in the same turn and will not be able to reach/crossover with the other
turns. Hence, this method reduces crossover.
Another method to improve the design is by changing the magnet of
the mover. Currently the magnets used have their poles on the flat surface
(back and front surface). The flux line is perpendicular to the coil but parallel
to the motion. To get a better output, magnets having its flux perpendicular to
both coil and motion should be used. Thus, to improve the design, the
magnets should have their flux line coming out of the curved surface and cut
across the coil perpendicularly.
30
Figure 5.1 Ring and Segmented Magnet
The diagram shows an example of a magnet that has its flux line
coming out from the curved surface. The outer and the inner curved surface
has different polarity. In between them, an iron core is inserted so that the
magnets will not push each other due to having the same polarity next to each
other.
31
5.2 CONCLUSION
Based on the consideration made on the sub factors discussed in the project, in
terms of Components Configuration, it can be concluded that the best design for the
Linear Generator would be the combination of:
• Moving Magnet (Mover-Stator Configuration)
• Magnet without Spacer (Magnet Configuration)
• Horizontally Coiled with Spacer (Stator Winding Configuration)
The study on Linear Generator’s application and design is a promising field to be
focused on. The potential of Linear Generator to become the main source of
renewable energy is great especially in Tidal Wave Power Generation. Given a
suitable condition, it may perform better and more reliable compared to Solar and
Wind Generator. Given a small size application, it may also replace the Piezoelectric
Generator.
32
References
[1] Oskar Danielson, Design of Linear Generator for Wave Energy Plant, Uppsala
University, Sweden
[2] Fuad Jamaludin, Design of Linear Generator, Universiti Teknology Petronas,
Malaysia
[3] “Electrical Generator Basics” http://www.wisc-online.com
[4]”Magnetic Field Line” http://www.ece.neu.edu/faculty/nian/mom/work.html
[5] “Analysis of Tubular Linear Generator for Free-Piston Engine”, Sun-Ki Hong, Ho-Yong
Choi, Jae-Won Lim, Hyo-Jae Lim and Hyung Kyo Jung, School of Engineering, Seoul
University, Shilim-Dong, Seoul, Korea, Hoseo University, Baebang-myun, Korea
[6] “Permanent Magnet Linear Alternator, Part II : Design Guidelines”, I.Boldea, Senior
Member IEEE, Polytechnic Institute, Romania, S.A Nasar, Fellow, IEEE, University of
Kentucky
[7] “Permanent Magnet Linear Generator for Renewable Energy Applications: Tubular vs
Four-sided Structure”, C.A Oprea, C.S Martis, F.N Jurca, D. Fodorean, I. Szabo, Technical
University of Cluj-Napoca, Romania
[8] “Novel Permanent Magnet Linear Generator for Wave Energy Converter”, Lorand
Szabo, Claudiu Oprea, Ioan Adrian Viorel, Karoly Agoston Biro, Technical University of
Cluj-Napoca, Romania
33
Appendices
34
Appendix
Design 1: Vertically Coiled Winding Output Current (A)
Run 1
Run 2
35
Run 3
Run 4
36
Design 1: Vertically Coiled Output Voltage (V)
Run 1
Run 2
37
Run 3
Run 4
38
Design 2: Horizontally Coiled Winding with Spacer Output Current (A)
Run 1
Run 2
39
Run 3
Run 4
40
Design 2: Horizontally Coiled Winding with Spacer Output Voltage (V)
Run 1
Run 2
41
Run 3
Run 4
42
Design 3: Horizontally Coiled Winding without Spacer ( Single Layer) Output
Current (A)
Run 1
Run 2
43
Run 3
Run 4
44
Design 3: Horizontally Coiled Winding without Spacer ( Single Layer) Output
Voltage (V)
Run 1
Run 2
45
Run 3
Run 4
46
Design 4; Horizontally Coiled Winding without Spacer (Multiple Layers) Output
Current (A)
Run 1
Run 2
47
Run 3
Run 4
48
Design 4; Horizontally Coiled Winding without Spacer (Multiple Layers) Output
Voltage (V)
Run 1
Run 2
49
Run 3
Run 4
50
Design 5: Horizontally Coiled Winding (Twisted) Output Current (A)
Run 1
Run 2
51
Run 3
Run 4
52
Design 5: Horizontally Coiled Winding (Twisted) Output Voltage (V)
Run 1
Run 2
53
Run 3
Run 4